Gideon Analytical Laboratories received electrolytic capacitors for chloride analysis according to a prior analysis technique for determining the presence of chloride. The chloride analysis technique was developed because chlorine is a known catalytic corrosive element on aluminum.
The analysis was performed using an SEM-EDS system giving elemental analysis in relation to the intensity of the element at a specific wavelength or energy level (Kev). Since Kev (energy levels) for specific elements do not change, these are used to identify the elements in the sample.
Gideon Analytical Laboratories received 100 capacitors and directed to analyze them via cross-sectional analysis. Capacitors store charges and frequently appear on PCBs. There are many types of capacitors; electrolytic capacitors are tantalum capacitors are fairly common. The goal was to discover any abnormalities or determine if there were no abnormalities.
Each capacitor was cross-sectioned and observed 15 to 20 times under 40-72x magnification during the sectioning process. At some point during the cross-sectioning process, pictures were taken to depict the internal quality of the ceramic structure and any cracks (mechanical, knit, Kirkendall voiding or other defects) that may be present.
Gideon Analytical Laboratories received several shorted PX6A07 silicon rectifiers for failure analysis. Two good devices were provided for reference and comparison. A semiconductor diode is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals. It conducts in the forward direction and is blocked in the reverse direction.
The good diodes were tested for conformance to the manufacturer’s specification. The good diodes performed per specification or exceeded electrical parameters listed.
This is a 6 amp plastic encapsulated silicon rectifier (PX6A07). Several of these high current diodes failed in the application.
The arrow points to the spot of one of the failures on one device after the epoxy and copper lead frame was removed.
The picture on the right is the anode. In the middle is the copper contact and the ring is actually the contact via solder to the P+ region of the die.
This is a class 2 inspection of a printed circuit board (PCB) using the IPC-A-610 Rev E. There is a bubble between the two solder joints of the opposite polarity battery terminals.
These enclosed mini-environments are known repositories for ions which will conduct when a voltage is applied. The leakage current drain is often dependent on the amount of moisture present in the atmosphere since the inside bubble environment will equilibrate with the surrounding atmosphere.
This vendor from China was in the process of qualification. There are solder dross and conductive flux underneath the conformal coating. Solder dross is highly conductive and flux will activate as an ionic conductor across leads, pads, terminals, etc.
Conformal coatings inhibit the crosstalk and ionic migration across the PCB surface. If, however, these contaminants reside on the board surface, the conformal coating cannot make contact with the solder mask and does not bond properly.
Gideon Analytical Laboratories received two 42-inch cables. One cable labeled with a mark where an intermittent open occurred and the other a new cable for comparison. Radiography cannot reveal any anomalies. Resistive measurements were taken along the wire to determine the location of the high resistance. The polypropylene was removed and several wires were inspected for holes or mechanical damage (kinks, exceeding bend radius, cuts, scoring, etc.) to the outer insulation.
Gideon Analytical Laboratories performed failure analysis on several polyimide flex circuits with corrosion near an IC. As seen in the picture above left, the corrosion appeared as black outgrowth along the trace lines. These flex circuits allow for greater functional capacity and miniaturization while maintaining high reliability through quality and consistency. They can be used in the aerospace, automotive, computer data and processing, and consumer FTIR.
The picture above right is of SEM-EDS spectral analysis showing the corrosion area.
Gideon Analytical Laboratories received three contaminated Buna-N diaphragms and several new ones for reference. These Buna-N diaphragms have a variety of applications, including in submersible level transmitters, actuary assemblies, air operated diaphragm pumps, and manual loading regulators. The goal was to identify the contamination and pinpoint its cause.
Upon examination under a stereo-zoom microscope, it was found that the surface of the sample contains a thick layer of a gel-like material.
Gideon Analytical Laboratories received several intermittent diodes failures and two good ones for comparison. The failed devices were checked for intermittent operation. The three diodes open-circuited between 65 and 80C. The lead frame makes contact with a solderable copper-clad steel plug under the glass.
This picture shows the lead frame to plug interconnect. If the solder fails to wet sufficiently the lead frame to plug interconnect, then intermittent opens can occur.
